Ah. Alrayyes et al., RADIOCESIUM IN HOT PARTICLES - SOLUBILITY VS CHEMICAL SPECIATION, Journal of environmental radioactivity, 21(2), 1993, pp. 143-151
In the case of a severe nuclear reactor accident, UO2 particles may be
emitted as a consequence of mechanical disintegration of the fuel. On
ce in the atmosphere, various physico-chemical reactions may then occu
r between the partially vitrified dioxide and vapours from the reactor
; these reactions are able to incorporate fission products into the UO
2 particles and reduce their availability to the environment. Caesium,
for example, which is usually very soluble, can react with fuel UO2 an
d iron from the reactor structures and be included in chemical forms s
uch as uranates or ferrites where its solubility is greatly reduced.